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Because of the overwhelming scattering of light in biological tissues, the spatial resolution and imaging depth of conventional fluorescent imaging is unsatisfactory. Therefore, we present a dual modality imaging technique by combining fluorescence imaging with high-resolution noninvasive photoacoustic tomography (PAT) for the study of an animal tumor model. PAT provides high-resolution structural...
High-intensity focused ultrasound (HIFU) has become a viable alternative for treatment of primary and metastatic liver tumors. We evaluated the effects of presence of a large blood vessel and its distance to the tumor on lesion size during HIFU heating. A finite element method (FEM) was used to obtain the temperature distribution for a transfer equation based on large blood vessels convection effect...
By cutting a spherical focused transducer into two coaxial and confocal transducer elements, a confocal complex transducer used in dual-frequency HIFU system was obtained. The lesion induced by dual-frequency HIFU in freshly excised porcine livers were obviously larger than that induced by conventional single-frequency HIFU at the same exposure conditions. The experiment results have also shown that...
We propose a new analysis method to detect phase coupling behaviour of the human gastric interdigestive pressure wave that has been acquired by a telemetric capsule-like mini-robot. The method is referred to as diagonal slice spectra, which are the Fourier transforms of the diagonal slices of the triple correlation and can detect the phase coupling and coupled components respectively. It is shown...
The study was to investigate thrombolysis in vivo with ultrasound, and to discuss effects of thrombolysis with ultrasound on the structure of erythrocyte and its safety threshold, under different ultrasound intensity and exposure time. The structure of erythrocyte in thrombus was evaluated under light microscope. The relationship between the structure of erythrocyte in thrombus and ultrasound intensity...
Wave propagation through the arterial system changes with age and disease state, and mutant mice are often used to study these conditions. We have developed several noninvasive ultrasonic techniques to measure blood velocity and vessel wall motion from which we can calculate aortic pulse wave velocity (PWV), local compliance, impedance spectra, characteristic impedance (Zc), augmentation index (AI),...
In the diagnosis and therapy of prostate cancer, it is critical to measure the volume of the prostate and locate its boundary. Three-dimensional transrectal ultrasound (3D TRUS) imaging has been demonstrated to be a useful technique to perform such a task. Due to image speckle as well as low contrast in ultrasound images, segmentation of the prostate in 3D US images is challenging. In this paper,...
The anterior cruciate ligament (ACL) functions as a mechanical stabilizer in the tibiofemoral joint. Over 250,000 Americans each year suffer ACL ruptures and tears, making the ACL the most commonly injured knee ligament. Methods which permit the in situ monitoring of changes in ACL graft mechanical properties during healing are needed. A long term goal in ACL reconstruction is to regenerate the ACL-bone...
Most technologies for tissue elasticity imaging are now based on measurement of stain distribution, since they are more suited to real-time processing than reconstruction of elastic modulus images. However, to obtain more quantitative information about tissue elastic properties, it is necessary to reconstruct tissue elastic modulus images. There, we developed a new method for reconstructing tissue...
As a differential diagnosis technique of living soft tissues, we are developing ultrasonic strain measurement-based shear modulus reconstruction methods. Previously, we reported a method utilizing the typical value of Poisson's ratio. However, as reconstruction errors were confirmed due to the difference between the original value and the set value, we proposed a method to reconstruct Poisson's ratio...
The main purpose of this paper is to develop a theoretical tool in order to fundamentally characterize the performance of Myocardial elastography and identify the optimal parameters to be used for the more reliable detection of ischemia or infarction. A complete representation of the left-ventricular function throughout an entire cardiac cycle was previously demonstrated through the use of a 3D finite-element...
Ultrasound and electromyography (EMG) are two of the most often used diagnostic tools for muscles. However, there is lack of a system for continuously capturing both signals with a synchronized procedure. This study presents a new system for this purpose. The system comprises an ultrasound scanner, a pulser/receiver, an EMG amplifier, and a PC with A/D converter cards for data acquisition and analysis...
Tissue stiffness is generally known to be associated with pathologic changes. Ultrasound indentation is able to assess the mechanical properties of soft tissues. Conventional ultrasound indentation devices use rigid flat-ended transducers to directly contact with the tissues and typically operate in the frequency ranging between 2 M Hz and 10 MHz. This paper introduced a novel ultrasound indentation...
Coronary artery disease (CAD) is a major cause of mortality in the western world. Although progress has been made in recent years for the noninvasive diagnosis of CAD, a widely available, inexpensive and effective diagnostic solution remains elusive. We have developed a novel ultrasound-based technology to detect and analyze the myocardial vibrations associated with diastolic murmurs produced by CAD...
The scattering mechanism of ultrasound in cancellous bone is investigated theoretically. The relationship of backscatter coefficient (BSC) in cancellous bone with frequency is analyzed in theoretical and experimental. The results of theory and experiment for cancellous bone of bovine tibiae, human calcaneus in vitro and in vivo showed that BSC is a non-linear function of frequency, increasing with...
Ultrasound-induced blood stasis has been observed for more than thirty years. Most of the literature has been focused on the health risks associated with this phenomenon and methods employed to prevent stasis from occurring during ultrasound imaging. To date, experimental observations have been either in vitro or invasive. The current work demonstrates ultrasound-induced blood stasis in murine tumor...
A study of microwave-induced thermoacoustic tomography is presented in this paper. Microwaves illuminate biological tissues to generate acoustic waves by thermoelastic expansion when electromagnetic energy was absorbed by human tissues. The generated acoustic waves carry information about different electromagnetic properties of different tissues which will be collected and processed to reconstruct...
We proposed an efficient method for classification of diffused liver diseases based on Gabor wavelet. It is well known that Gabor wavelets attain maximum joint space-frequency resolution which is highly significant in the process of texture extraction and presentation. This property has been explored here as the proposed method outperforms the classification rate obtained by using dyadic wavelets...
The aim of this paper was to investigate the usefulness of multiscale morphological analysis in the assessment of atherosclerotic carotid plagues. Ultrasound images were recorded from 137 asymptomatic and 137 symptomatic plaques and were converted to binary images at low, middle and high intensity intervals based on structural morphology . Low images represent low intensity regions corresponding to...
In this report, we propose to reconstruct thermal properties such as thermal conductivity and thermal diffusivity in addition to the mechanical properties for diagnosis and treatment (planning). Temperature distribution can be measured by ultrasonic imaging and MRI. Provided that the reference values of thermal properties are given in the ROI as initial conditions, by solving the simultaneous first...
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